Stackable container system



FIG. 1 is a perspective view of an ornamental design for a stackable container system;

FIG. 2 is a front elevational view thereof;

FIG. 3 is rear elevational view thereof;

FIG. 4 is a left elevational view thereof;

FIG. 5 is a right elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The portions of the stackable container system shown in broken lines form no part of the claimed design. 

CLAIM I claim the ornamental design for a stackable container system, as shown and described. 